Applied Mechanics and Materials Vols. 130-134

Abstract: We put forward a process of automatic airport extraction based on the characteristics of high resolution remote sensing images. First, through image enhancement algorithm, the contrast of target and background is enhanced. Second, we can extract the possible airport through the algorithms of Ostu segmentation, mathematical morphology corrosion and region-labeling. Finally, combined with the geometric structure of the runway, the airfield runway can be extracted through the algorithms of edge detection, progressive probability Hough transform and line connection. Then the possible airport can be verified by the extracted airfield runway. In the process, we proposed an improved fuzzy enhancement algorithm for image enhancement. This algorithm has good effect on the image enhancement and has strong robustness. The results of the experiment indicate that the process of automatic airport extraction is robust and has the advantages of high speed and degree of automation.

Abstract: In recent years, as affected by climate change and human activities, wind speed shows an obvious downward trend. According to the following three correction methods : correction of the cluster analysis and mean equality, correction of the trend extraction, and the combination of the aforementioned two methods, the wind speed series which meets the consistency requirement of frequency calculation is obtained in this paper. Practical application shows that the correction methods have good adaptability, correction result and great practical value.

Abstract: Power electronics converters play an important role in realization and performance improvement of electrical power system. With the demand for new power resource and better power supply quality, more and more distributed energy resources (DERs) come into practice. As a new network configuration, microgrid attracts much attention, consequently lots of new power electronics devices and engineering experiments are brought forward. The paper focus on the multilevel inverters in microgrid, discusses its topologies and characteristics. A model predictive controller is designed to decrease common mode voltages and errors between the capacitor voltages and their reference values. Finally, simulation diagram, parameters and results using software PLECS are provided to demonstrate the merits of multilevel inverters and the validity of proposed control method.

Abstract: The back electromotive force (EMF) waveform of brushless dc motor (BLDCM) is trapezoid. But it is not absolutely trapezoid because of motor manufacturing. In this paper, a method of modeling for BLDCM with nonideal back EMF is presented. Eighteen states during an electric angle cycle are obtained after the nonideal back EMF of BLDCM is analyzed. The S-Function of MATLAB is used to generate the nonideal back EMF according to rotor speed and position. The pulse width modulation (PWM) current control of BLDCM is adopted. Simulated results validate the method.

Abstract: This paper mainly discussed the non-linear characteristics of photovoltaic cell and the importance of maximum power point tracking (MPPT) strategy. Most of MPPT control methods had the shortcomings of inaccuracy, tardiness, complexity and big fluctuations nearby the MPP which greatly reduced the efficiency of large photovoltaic power generation system. Double fuzzy logic control (DFLC) method can solve this problem The judgment condition of choosing FLC was listed in which FLC 1 targeted to less shake and made the curve become more smooth and steady nearby the MPP, FLC 2 was combined by fuzzy control and PID algorithm, and both of them aim to realize the optimization control of PV system. The results of simulation show that the proposed control strategy can track the MPP of PV system very accurately and quickly along with the rapid change of the ambient environment.

Abstract: A scheme is proposed to realize remote control of embedded instrument without operation system under the mode of B/S structure in view of its self-limitation. Advanced LXI bus technology is usually employed to replace the traditional bus technologies, by which the remote network control can be realized. Due to its, small resource characteristics of embedded instrument, LwIP protocol stack is transplanted into the instrument for realization of the simple TCP/IP protocol function, Web server function is applied to the instrument. The method takes existing low-end instrument as a foundation, combines CGI with the embedded instrument for interactive operation and finally realizes the remote control of embedded instrument through LAN interface.

Abstract: Tunnel project contains complex and diverse risk factors. Risk management has an important role on tunneling engineering projects. Risk management is based on risk identification. Only with sufficient knowledge of risk can we analyze,evaluate and control the risk .Traditional risk identification methods are generally targeted at a certain stage of the tunnel project or a particular content of the tunnel project. It can not consider all factors of the tunnel projects. This paper presents a new risk identification method - hierarchical holographic modeling. The method provides a multi-angle decomposition to the perspective of the tunnel features and in order to find the tunnel project risk source. It can provide a basis for risk management.

Abstract: A differential phase error detector is inserted in the carrier loop structure for improving the dynamic performance of the loop in GNSS receiver in this paper. It is used to detect the abnormal phase jitter and amplify the adjusting increment for fast tracking. In order to avoid the differential detector amplifying noise interference in locking, fuzzy logical theory is introduced into the loop to control the amplification caused by the differential detector. Finally simulations show that the proposed design achieves high dynamic performance with effectively speeding up the tracking and widening the dynamic stress range.

Abstract: A control system for water level of boiler steam drum based on DSP microprocessor is designed in this paper. The technique of fuzzy control was applied to controlling the water level of the steam drum, the operational principle and application of the fuzzy-PID arithmetic are described. The water level controller with good control effect is developed. Firstly the hardware structure of system is introduced in the paper and then investigates the fuzzy-PID arithmetic carry out, and finally, the simplified program flowchart are given.

Abstract: This paper combines the fuzzy control theory with the specific control object .We use MATLAB as the simulation platform ,and detailed research the application of the fuzzy adaptive PID control algorithm and the fuzzy adaptive - PID controller in the constant pressure water supply control system , provides a solution for the delay and nonlinear system.